1. Field of the Invention
The invention relates to an apparatus for detecting the position or temperature of an object by using a pyroelectric type infrared sensor.
2. Description of the Prior Art
As a pyroelectric-type infrared detecting apparatus, there has been hitherto known a device in which an object is mechanically scanned with a scanning reflecting mirror using a point sensor or a linear array sensor or a device in which the whole object area is covered by a two-dimensional array sensor. However, these devices have drawbacks in that the former devices which use a scanning reflecting mirror are large in size and are high in cost because of their complicated structure and the latter devices, which use a two-dimensional array sensor to obtain a wide range of view, require a wide-angle infrared lens which is difficult to fabricate and is therefore expensive. Particularly, a device, wherein the temperature of an object is measured by using a pyro-electric sensor, is large in size since the measurement must be carried out by interrupting incident infrared rays using of an optical chopper to determine the difference between the value when the chopper is opened and the value when the chopper is closed.
Recently, a pyro-electric type infrared detecting device of the scanning type has been studied as an industrial measuring device such as a line scanner or a sensor for detecting indoor status for crime prevention, diaster prevention or air conditioning and the like. An example of such a device is disclosed in Japanese unexamined patent publication No. 53-41279/1978.
Hereinafter, an example of a conventional pyro-electric type infrared detecting device will be explained with reference to the drawings of this application.
FIG. 7 shows a conventional scanning type non-contact temperature measuring apparatus. In FIG. 7, element 21 is a motor rotating at a constant speed; element 22 is a rotational axis of the motor; element 23 is a rotating disk; element 24 is a pin; element 25 is a scanning reflection mirror; element 26 is a supporting shaft; element 27 is a connecting arm; element 28 is an object to be measured; element is a reflecting mirror; element 30 is a reflecting mirror; element 31 is a rotating sector for interrupting infrared rays; element 32 is a lens for collecting light, and element 33 is an infrared ray detector.
With referrence to the scanning type non-contact temperature measuring device constituted as above, the action of the device will be explained below.
The rotational movement of the motor 21 is transmitted to the scanning reflecting mirror 25 through the connecting arm 27 to cause reciprocal movement of the scanning reflecting mirror 25. The infrared ray emitted from each point of measuring object scanned by reciprocal movement of the scanning reflecting mirror 25 is reflected by the reflecting mirrors 29 and 30, and collected by the collecting lens 33 and sent to the infrared detector 32. The rotation sector 31 provided in front of the infrared ray detector 33 is rotated by the motor 21, and the temperature can be measured since a groove is formed to transmit the infrared ray at one position of the scanning reflecting mirror.
However, the above mentioned structure, wherein the scanning reflecting mirror 25 is arranged in front of collecting lens 32, involves drawbacks in that the device is difficult to be installed or to be made compact in size due to its complicated driving system construction, or in that while the angle of view of the collecting lens can be made wide in the direction of rotation, the angle of view in the direction of the rotation axis is significantly limited for the lens.